Unisource high-strength ultrasound-assisted method for casting large-specification 2xxx series aluminium alloy round ingot

ABSTRACT

In the technical field of metal melting, a unisource high-strength ultrasound-assisted method for casting large-specification 2XXX series aluminum alloy round ingots applies in an ingot guiding process, a unisource high-strength ultrasonic vibration system to the center of a hot-top crystallizer, ultrasound directly acts on the center position of a crystallizer, and enough ultrasonic field energy is provided for a melt by controlling the power of the ultrasonic vibration system, so that an aluminum alloy solidification process is implemented under the effect of ultrasound, homogenization of microstructures and components of ingots is promoted, and the existing problems that microstructures are thick and crystal phases are enriched due to slow cooling of centers of large-specification round ingots are effectively solved, meanwhile, the problems of great operation difficulty and heavy workload during multisource ultrasonic coupling are avoided.

TECHNICAL FIELD

The present invention relates to the technical field of metal smelting,and particularly relates to a unisource high-strengthultrasound-assisted method for casting large-specification 2XXX seriesaluminum alloy round ingots.

BACKGROUND

Aluminium alloy ring-shaped parts and cylindrical parts as mainload-carrying structural parts in aerospace structural parts arecomplicated in stress state and high in comprehensive performances anddimensional precision requirement, currently, process schemes forpreparing high-performance aluminium alloy ring-shaped parts/cylindricalparts at home and abroad mainly adopt integrated manufacturing,therefore, a preparation technology for original high-quality ingots isof great importance, and non-uniformity of microdefects ormicrostructures in original blanks will be inherited to subsequentlycaused difference of performances of ring-shaped parts/cylindricalparts. Especially, at present, aerospace structural parts in Chinadevelop to be large-scale, the required round ingot diameter is larger,while along with increase of the diameter of aluminium alloy roundingots, problems and conflicts in a casting process are more prominent,for example, extremely non-uniform distribution of melt temperaturefield and flow field caused by the problems of large spatial scaleeffect, non-equilibrium solidification environment and nonuniformity ofblank component structures and forming interfaces, finally causingextremely nonuniform distribution of ingot microstructures and elements;especially, the core part of the ingot is cooled slowly, easily formingthick solidified microstructures and network-shaped AlCu eutecticphases, and easily forming the defects of looseness, air holes and thelike.

Targeted to the problems of great internal and external temperaturedifference, serious composition segregation, thick and nonuniformmicrostructures, and enrichment and segregation of crystalline phases ofthe core parts of conventional semi-continuous casting ingots, atpresent, aluminium alloy production enterprises mainly apply a refinerto refine grain microstructures, and optimize casting process parameterssuch as casting temperature, casting rate and cooling water flow toweaken segregation and refine microstructures; part of scientificresearch institutions and colleges and universities adopt physicalfields such as electromagnetism to act on a solidification process toregulate microstructure and composition uniformity.

However, along with increase of specifications and dimensions of ingots,increase of use amount of the refiner will cause substantial increase ofcost, and in use, too little refiner cannot reach an optimal refiningrequirement, while excessive refiner will cause a phenomenon of“poisoning”, that is, along with increase of content of the refiner,after the refining capability reaches a certain degree, increase ofcontent cannot further improve the refining capability, moreover,excessive refiner forms segregation very easily, intensifying thenonuniformity degree of ingot microstructures. While for anelectromagnetic stirring system, an electromagnetic device is mainlyprovided at the outer periphery of a die to arouse macroscopic flow of ametal melt by electromagnetic force, so as to promote the uniformity ofa melt temperature field; electromagnetic stirring systems of differentspecifications need to be customized and mounted targeted to differentdies, resulting in enormous expense; moreover, electromagnetic stirringprocess parameters adopted for ingots of different specifications needto be debugged and optimized, and too strong stirring capability maycause leakage of metal aluminium liquid, causing safety accidents.

Moreover, an ultrasound-assisted casting technology also starts to beapplied to production of large-specification aluminium alloy ingots,while higher ultrasonic energy is generally needed for solidification oflarge-dimension ingots, therefore, combined action of multiple groups ofultrasound is needed, application of multiple ultrasonic vibrationsources needs to be optimized and controlled in a targeted mode, aprocess for intercoordination and matching optimization betweenparameters of different frequencies, powers, phase differences andultrasonic distances and positions is complicated, and workload isheavier.

SUMMARY

The present invention is directed to provide a unisource high-strengthultrasound-assisted method for casting large-specification 2XXX seriesaluminum alloy round ingots, the method provided by the presentinvention being convenient in operation, saved in cost and high inproduction efficiency by processing a melt at the center position of acrystallizer by adopting an ultrasonic vibration source.

In order to achieve the foregoing purpose of the present invention, thepresent invention provides the following technical scheme:

A unisource high-strength ultrasound-assisted method for castinglarge-specification 2XXX series aluminum alloy round ingots, includingthe following steps:

performing solidification and ingot guiding by enabling melt of 2XXXseries aluminium alloy to flow into a hot-top crystallizer, after ingotguiding is started, applying a set of ultrasonic vibration system to thecenter of a crystallizer of the hot-top crystallizer, and when castingis about to end, removing the ultrasonic vibration system, to obtain alarge-specification 2XXX series aluminum alloy round ingot;

power of the ultrasonic vibration system being 2˜4 kw; and diameter ofthe large-specification 2XXX series aluminum alloy round ingot being≥500 mm

Optimally, the diameter of the large-specification 2XXX series aluminumalloy round ingot is 500-1380 mm

Optimally, the ultrasonic vibration system includes an ultrasonictransducer, an amplitude transformer and a radiation rod, length of theradiation rod being 490 mm

Optimally, the depth of the radiation rod of the ultrasonic vibrationsystem immersing into the melt is 15˜480 mm

Optimally, frequency of the ultrasonic vibration system is 15˜30 khz.

Optimally, an applying mode of the ultrasonic vibration system is tovertically guide the radiation rod into the melt from top to bottom.

Optimally, before applying the ultrasonic vibration system, the methodalso includes: preheating the radiation rod of the ultrasonic vibrationsystem; the preheating temperature being not lower than 350° C.

The present invention provides a unisource high-strengthultrasound-assisted method for casting large-specification 2XXX seriesaluminum alloy round ingots, according to the present invention, in aningot guiding process, a unisource high-strength ultrasonic vibrationsystem is applied to the center of a hot-top crystallizer, ultrasounddirectly acts on the center position of a crystallizer, and enoughultrasonic field energy is provided for a melt by controlling the powerof the ultrasonic vibration system, so that an aluminium alloysolidification process is implemented under the effect of ultrasound,homogenization of microstructures and components of ingots is promoted,and the existing problems that microstructures are thick and crystalphases are enriched due to slow cooling of centers oflarge-specification round ingots are effectively solved, meanwhile, theproblems of great operation difficulty and heavy workload duringmultisource ultrasonic coupling are avoided; according to the presentinvention, the quantity of adopted ultrasonic sources is few, operationis convenient, cost is saved, and production efficiency can beeffectively improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a unisource high-strengthultrasound-assisted device for casting large-specification 2XXX seriesaluminum alloy round ingots, wherein 1—smelting furnace, 2—diversiontrench, 3—aluminium melt, 4—hot-top heat preservation cap,5—crystallizer, 6—cooling water, 7-ultrasonic vibration system,8-aluminium ingot, 9-ingot guiding plate;

FIG. 2 is a casting site map after applying ultrasound in embodiment 1;

FIG. 3 is low-power detection results of a common ingot and anultrasonic ingot in embodiment 1;

FIG. 4 is a low-power microstructure diagram of radial directions of thecommon ingot and the ultrasonic ingot in embodiment 1 from the core partto the side part;

FIG. 5 is radial Cu content distribution of the common ingot and theultrasonic ingot in embodiment 1; and

FIG. 6 is a crystal phase comparison diagram of the common ingot and theultrasonic ingot in embodiment 1 in different positions.

DESCRIPTION OF THE EMBODIMENTS

The present invention provides a unisource high-strengthultrasound-assisted method for casting large-specification 2XXX seriesaluminum alloy round ingots, including the following steps:

performing solidification and ingot guiding by enabling melt of 2XXXseries aluminium alloy to flow into a hot-top crystallizer, after ingotguiding is started, applying a set of ultrasonic vibration system to thecenter of a crystallizer of the hot-top crystallizer, and performingingot guiding under the action of the ultrasonic vibration system, andwhen casting is about to end, removing the ultrasonic vibration system,to obtain a large-specification 2XXX series aluminum alloy round ingot.

According to the present invention, the diameter of thelarge-specification 2XXX series aluminum alloy round ingot is ≥500 mm,optimally, 500˜1380 mm, more optimally, 600˜1250 mm.

According to the present invention, there is no special requirement fora preparation method of the melt of the 2XXX series aluminum alloy, justa method familiar to a person skilled in the art may be adopted. Inspecific embodiments of the present invention, a preparation process ofthe melt of the 2XXX series aluminum alloy optimally includesdispensing, smelting, component adjustment and purification treatment.

According to the present invention, the dispensing may be performed justaccording to a basic principle in a nominal component specificationscope of alloy designation, and alloy raw materials used in dispensinginclude pure aluminium, aluminium-copper intermediate alloy andintermediate alloy of other elements, specific variety being selectedaccording to components of a target alloy ingot.

According to the present invention, in the smelting process, optimally,firstly, feeding a pure aluminium ingot into a furnace, rising furnacetemperature to 750° C. and preserving heat until the aluminium ingot iscompletely smelted, and then gradually adding other metals in batches,and slagging off and stirring after all the metals are smelted.

According to the present invention, the component adjustmentspecifically includes: sampling to-be-tested components after all alloyraw materials are smelted, and supplementing material or dilutingaccording to a component test result, so as to ensure that meltcomponent content meets the design requirement, and standing for aperiod of time after component adjustment is completed and thendischarging out of the furnace.

According to the present invention, the purification treatment optimallyincludes online degassing and impurity removal, specifically, an onlinedegassing and filtering device is provided in a diversion trench betweenthe smelting furnace and the crystallizer. According to the presentinvention, a rotating nozzle inert gas flotation method (called as anSNIF melt purifying method for short) is optimally adopted for thedegassing, specifically, argon is introduced into a rotating nozzle in adegassing box which can be heated for heat preservation to be sprayedinto an aluminium melt, and by virtue of the high speed rotation of thenozzle, argon is dispersed to be tiny bubbles, to stir the melt tointensify mass and heat transfer, so as to play the roles of degassingand deslagging in a floating-up process. According to the presentinvention, a foamed ceramic filter box is optimally adopted forfiltering to remove impurities, a spongy ceramic filter in the filterbox is mainly made from materials such as aluminium oxide and chromiumoxide, and a foamed ceramic filtering and purification principle belongsto a deep filtering mechanism, is large in filtering capability, and isapplicable to filtering and purification in continuous casting androll-casting production; in specific embodiments of the presentinvention, optimally, a refiner is applied to a diversion trench, so asto further purify a melt, and refine grains; according to the presentinvention, there is no special requirement for the variety of therefiner, just a refiner familiar to a person skilled in the art may beused.

According to the present invention, there is no special requirement forspecific operation parameters of the degassing and filtering, justneeding to operate according to a method familiar to a person skilled inthe art.

Moreover, in a smelting process, smelting time and chemical componentsshould be strictly controlled, and on the premise of ensuring that thealloy is completely smelted, shortening labor hour and reducing burningloss as far as possible.

A melt of the 2XXX series aluminum alloy flows into a hot-topcrystallizer to be be subject to solidification and ingot guiding, afteringot guiding is started, a set of ultrasonic vibration system isapplied to the center of a crystallizer of the hot-top crystallizer, andwhen casting is about to end, the ultrasonic vibration system isremoved, to obtain a large-specification 2XXX series aluminum alloyround ingot. According to the present invention, there is no specialrequirement for the structure of the hot-top crystallizer, just ahot-top crystallizer familiar to a person skilled in the art may beused. According to the present invention, the hot-top crystallizerincludes a hot-top heat preservation cap, a crystallizer, an ingotguiding plate and a cooling water system (a structure being as shown inFIG. 1); after being smelted in a smelting furnace, a melt enters thehot-top crystallizer from a diversion trench, is primarily cooled by thecooling water system firstly to be solidified to be a shell in thehot-top crystallizer, and then along with the downward traction of theingot guiding device, the solidified shell moves downwards and is cooledfor a second time directly by cooling water to be further solidified, soas to form an ingot. According to the present invention, after ingotguiding is started, an ultrasonic vibration system is applied, and anapplying mode is optimally to vertically guide a radiation rod into amelt from top to bottom, ensuring that the liquid level of the melt inthe crystallizer is steady when the radiation rod is immersed into themelt; according to the present invention, optimally, after ingot guidingis started, an ultrasonic vibration system is applied when the length ofthe ingot is 200 mm

According to the present invention, the ultrasonic vibration system iscomposed of an ultrasonic transducer, an amplitude transformer and aradiation rod, wherein the transducer is connected with an ultrasonicpower source to generate ultrasonic vibration, an amplitude transformermagnifies amplitude, while the radiation rod directly contacts with anacting object to emit ultrasonic wave; length of the radiation rod beingoptimally 490 mm. According to the present invention, the depth of theradiation rod of the ultrasonic vibration system immersing into the meltis 15˜480 mm, optimally, 50˜450 mm, further optimally, 100˜400 mm,frequency of the ultrasonic vibration system is optimally 10˜30 khz,more optimally, 18˜28 kHz, further optimally, 19˜21 kHz, and power isoptimally 2˜4 kw, more optimally, 2.5˜3.5 kw. According to the presentinvention, the frequency and power of the ultrasonic vibration systemare controlled within the foregoing scope, so as to provide enoughultrasonic field energy, and promote homogenization of themicrostructure and components of the ingot.

Before ultrasonic vibration is applied, according to the presentinvention, optimally, the radiation rod of the ultrasonic vibrationsystem is preheated; the preheating temperature is optimally not lowerthan 350° C., more optimally, is 400˜450° C.; before preheating, thepresent invention also optimally includes: cleaning the surface of theradiation rod, and there is no special requirement for the surfacecleaning, just needing to thoroughly clean impurities on the surface ofthe radiation rod; after preheating, the present invention alsooptimally includes: performing no-load debugging on the ultrasonicvibration system, and by no-load debugging, the present inventionensures that the amplitude output of the end face of the radiation rodof the ultrasonic vibration system is ≥15 micrometers.

In the whole process of processing an aluminium alloy melt by ultrasonicvibration, stability of ultrasonic parameters is ensured by automatictracking and adjusting functions of an ultrasonic power system, and theultrasonic vibration system should not be disturbed in an operatingprocess, so as to avoid disturbance of ultrasonic parameters andfluctuation of aluminium liquid.

According to the present invention, there is no special requirement forthe casting temperature, casting speed, spraying water pressure andcooling water flow of a melt in the crystallizer, just needing to setaccording to specific conditions.

When casting is about to end, according to the present invention, anultrasonic vibration system in the hot-top crystallizer is removed, andin specific embodiments of the present invention, specific removal timeof the ultrasonic vibration system can be determined according to thespecification of the ingot and remaining height of the melt in thecrystallizer, just needing to ensure that ingot is smoothly ended andformed. When the ultrasonic vibration system is removed, optimally,turning off the ultrasonic power source firstly, then slowly lifting upthe ultrasonic vibration system by using a lifting table, and moving toa safety zone, keeping steady in a moving process, so as to avoidfluctuation of the aluminium liquid and rolling-in of an oxidation film;a removed ultrasonic vibration system should be further ventilated tocool and the surface of the radiation rod is thoroughly cleaned.

According to the present invention, a unisource ultrasonic vibrationsystem is applied to the center of a hot-top crystallizer, and effectssuch as cavitation, acoustic streaming and stirring caused by ultrasonicvibration act on the interior of an aluminium melt, so as to accelerateheat transfer and convection of the melt, promote uniformity ofsolidification temperature field and flow field, and finally achieve thepurpose of controlling the microstructure and components of the ingot tobe uniform.

According to the present invention, the action of ultrasound in acrystallizer can be divided into two parts according to actingpositions, which are respectively actions on a liquid metal zone and asolid-liquid mixed zone in a smelting pool. In the liquid metal zone, acavitation effect generated by ultrasonic vibration firstly has effectsof digassing and impurity removal. There are usually many microcosmicinsoluble solid heterogeneous particles (such as oxide, carbide, nitrideand the like) in a metal melt, in actual production, crystal nucleus arepreferably formed by attaching to the surfaces of the heterogeneousparticles, however, in general conditions, because the surfaces of theheterogeneous particles have some surface defects such as narrow cracks,grooves, bosses and fissures, most heterogeneous particles are in aninert state and fail to become effective heterogeneous nucleus toparticipate in nucleus forming. However, under the cavitation effect ofhigh-strength ultrasound, impact pressure caused by cavitation bubblecollapse impacts the surfaces of particles constantly, to play a role ofcleaning the surfaces of the heterogeneous particles; cavitation bubblesare accompanies with a series of two-order phenomena in an oscillatingprocess, for example, enabling liquid itself to generate ring current,causing vibrating bubbles to have very high velocity gradient andviscous stress, and prompting damage and falling-off of dirt on thesurface of a cleaned member; meanwhile, high-speed microjet generated byultrasonic cavitation can remove or weaken a dirt bed on the boundary ofa solid surface to go deep into holes, groove, slits and micropores inthe surfaces of particles, so as to improve the wettability of theheterogeneous particles; moreover, ultrasonic vibration also can arousesevere vibration of the heterogeneous particles in metal liquid, so asto improve the wettability of the heterogeneous particles in the liquidmetal. In a word, applying of an ultrasonic field has a severeactivation effect for these heterogeneous particles, and can transformthe heterogeneous particles into effective crystal nucleus toparticipate in a solidification and nucleus forming process. Moreover,the acoustic streaming effect of ultrasound can drive disturbance of asmelting pool flow field, so as to promote uniform distribution of atemperature field on one hand, and uniformly disperse activatedheterogeneous particles to different positions on the other hand, andthus promoting uniformity of a temperature field, a flow field andsolidified microstructures in a smelting pool.

In a solid-liquid mixed zone (that is, a solidification front zone),when the ultrasonic depth is constantly increased to directly act anultrasonic cavitation effect to a solidification front, microjet andhigh-frequency vibration generated by ultrasonic cavitation may play theroles of impacting and vibrating for primary dendritic crystals andsecondary dendritic crystals, possibly causing falling-off of thesecondary dendritic crystals from the neck, and the falling-off freedendritic crystals are more liable to be uniformly distributed in asmelting pool along with the stirring action of ultrasonic acousticstreaming, so as to increase nucleus forming nucleus, and refine asolidified microstructure. Meanwhile, when ultrasonic vibration acts ona solid-liquid coexisting zone as a vibration energy, it may also arouseco-frequency resonance so as to cause a lot of primary crystals growingto a same dimension to generate common vibration, inhibit further growthof the crystals, promote uniformity of crystal microstructure, andfinally play the roles of refining grains, reducing content of alloyingelements of microstructures of the core part and inhibiting enrichmentof thick crystal phases.

According to the present invention, a unisource high-strength ultrasonicsystem is applied to the center of a crystallizer, which uses fewultrasonic sources, is convenient to operate and saves cost, and caneffectively solve the problem of great difficulty in operation controlof the prior art and increase the production efficiency on the basis ofensuring ingot quality.

The following describes the scheme provided by the present invention indetails with reference to embodiments, however, these cannot beunderstood as limitation to the protection scope of the presentinvention.

Embodiment 1

Ultrasonic semi-continuous casting of Φ1100 mm 2219 aluminium alloy withlength of 3000 mm

1. A Casting Process

1) Debugging and Preparation Before Casting

Detecting 20-ton casting equipment, ensuring that □ in the part of asmelting furnace, a heating device, an electromagnetic stirring deviceand a furnace dumping power device operate normally; □ in a diversiontrench and an online degassing and impurity removal part, checkingwhether a deslagging and heating device works normally, whether arotating nozzle is normal and available, whether a filter plate isabraded seriously, and whether a refiner wire feeder works normally, andensuring that the diversion trench is thoroughly cleaned, withoutaluminium residue and the like; □ in the part of a crystallizer:checking whether a hot-top cap and a graphite crystallizer are seriouslyabraded and need to be changed, and whether an ingot guiding deviceworks normally, and ensuring that an oil-gas lubrication system and acooling water system work normally.

2) Alloy Matching and Smelting

Strictly controlling smelting time and chemical components in a smeltingprocess, and on the premise of ensuring that alloy is completelysmelted, shortening labor hour and reducing burning loss as far aspossible. Specific operations are: firstly feeding a pure aluminiumingot into a furnace, starting heating equipment to rise furnacetemperature to 750° C. and preserving heat for a period of time toensure that the aluminium ingot is completely smelted, then graduallyadding other metals in batches, and after the metals are completelysmelted, sampling to-be-tested components by electromagnetic andmanpower stirring in match with slagging-off and stirring, thenselecting to supplement material or dilute according to component testresults, standing for 10 min after refining is completed, and thendischarging out of a furnace, the scope of ally components being asshown in table 1.

TABLE 1 Aluminium alloy element matching table (mass fraction, %) Alloyelements Si Fe Cu Mn Mg Zn Ti V Zr Al Specialized <0.2 <0.3 5.8~6.80.2~0.4 <0.02 <0.1 0.02~0.1 0.05~0.15 0.1~0.25 Balance scope (%) a 0.0060.03 5.96 0.38 0.002 0.005 0.059 0.07 0.11 Balance

3) Online Degassing and Impurity Removal of Aluminium Liquid

Providing an online degassing and filtering device in a diversion trenchbetween the smelting furnace and the crystallizer. An inert gasflotation method (called as SNIF melt purifying method for short) with arotating nozzle is adopted for degassing. A foamed ceramic filteringmethod is adopted for filtering for deslagging.

4) Ultrasonic Casting

Performing ultrasonic processing on the rear half section of an ingot ina semi-continuous casting process, and finally comparing microstructuresof two segments of the ingot, specific steps of ultrasound-assistedcasting experiment are as follows:

Preheating a diversion trench, the inner wall of a crystallizer and anultrasonic radiation rod. Opening a furnace mouth after temperature issteady and tilting the smelting furnace for pouring, opening coolingwater of the crystallizer, starting an ingot guiding device afteraluminium liquid flows into the crystallizer for a certain height,meanwhile, opening secondary cooling water to spray the system, at themoment, an ingot guiding plate moves downwards to pull down the ingot,starting semi-continuous casting, and when the length of the ingot is1500 mm, vertically applying a set of ultrasonic vibration system from aposition above the center of the crystallizer and vibrating, wherein thedepth of the ultrasonic radiation rod immersing into the aluminiumliquid is about 200 mm, frequency is 30 khz, and power is 4 kw, and whencasting is about to end, removing the ultrasonic vibration system, toobtain an aluminium alloy ingot, wherein the upper half section (0˜1500mm) of the obtained ingot is common ingot, and the lower half section(1500˜3000 mm) is ultrasonic ingot.

A schematic diagram of a device used in the present embodiment is asshown in FIG. 1, the right of FIG. 1 is a schematic diagram of anapplying position of the ultrasonic vibration system in thecrystallizer, and r represents the radius of the crystallizer; a castingsite after being applied with ultrasound is as shown in FIG. 2.

2. Microstructure Analysis

FIG. 3 is low-power detection results of common ingot and ultrasonicingot, it is known from FIG. 3 that the grain size of the ultrasonicingot is reduced, microstructures become tiny and are uniformlydistributed, and the center of the ingot is about in level 2.5; whilethe center of the common ingot is in level 4. A further enlarged drawingis as shown in FIG. 4, in FIG. 4, (a) is a low-power microstructurediagram of the common ingot from the core part to the side part, (b) isa low-power microstructure diagram of the ultrasonic ingot from the corepart to the side part; and it is obviously known from FIG. 4 that themicrostructure of the core part of the common ingot is thick.

FIG. 5 is radial Cu content distribution of the common ingot and theultrasonic ingot, wherein (a) is common ingot, (b) is ultrasonic ingot;it is known from the result that the ultrasonic ingot is uniformlydistributed, and it is known by computation that the maximum radialsegregation rate of Cu element of the common ingot is 7%, and that ofthe ultrasonic ingot is 5%, indicating that the ultrasonic ingot issmaller in deviation, and uniform in components.

FIG. 6 is a crystal phase comparison diagram of the common ingot and theultrasonic ingot, wherein R represents the radius of an aluminium alloyround ingot, and it is known from FIG. 6 that the crystal phasemicrostructures of the ultrasonic ingot are tiny and uniform; while theintra-crystal crystal phases of the common ingot are thick and aredistributed in a network form.

It is known from the foregoing embodiment that according to the presentinvention, a unisource high-strength ultrasonic vibration system isapplied to the center of the hot-top crystallizer, so as to promote thehomogenization of the microstructures and components of ingots and grainrefining, to obtain high-quality aluminium alloy ingots; moreover,according to to the present invention, few ultrasonic sources areadopted, operation is convenient, and cost is saved, the problem ofgreat difficulty in operation control in multisource ultrasonic couplingcan be effectively solved, and production efficiency is increased.

The foregoing descriptions are merely preferred implementation modes ofthe present invention, it should be noted that a person of ordinaryskill in the art may make some improvements and modifications withoutdeparting from the principle of the present disclosure, and these allshould be deemed as falling within the protection scope of the presentinvention.

1. A unisource high-strength ultrasound-assisted method for castinglarge-specification 2XXX series aluminum alloy round ingots, comprisingthe following steps: performing solidification and ingot guiding byenabling melt of 2XXX series aluminum alloy to flow into a hot-topcrystallizer, after ingot guiding is started, applying a set ofultrasonic vibration system to the center of a crystallizer of thehot-top crystallizer, and when casting is about to end, removing theultrasonic vibration system, to obtain a large-specification 2XXX seriesaluminum alloy round ingot; wherein power of the ultrasonic vibrationsystem being is 2˜4 kw; and wherein diameter of the large-specification2XXX series aluminum alloy round ingot is ≥500 mm.
 2. The methodaccording to claim 1, wherein the diameter of the large-specification2XXX series aluminum alloy round ingot is 500-1380 mm.
 3. The methodaccording to claim 1, wherein the ultrasonic vibration system comprisesan ultrasonic transducer, an amplitude transformer and a radiation rod,length of the radiation rod being 490 mm.
 4. The method according toclaim 3, wherein the depth of the radiation rod of the ultrasonicvibration system immersing into the melt is 15˜480 mm.
 5. The methodaccording to claim 1, wherein frequency of the ultrasonic vibrationsystem is 15˜30 khz.
 6. The method according to claim 1, wherein anapplying mode of the ultrasonic vibration system is to vertically guidethe radiation rod into the melt from top to bottom.
 7. The methodaccording to claim 1, wherein before applying the ultrasonic vibrationsystem, also comprising: preheating the radiation rod of the ultrasonicvibration system; wherein the preheating temperature being is not lowerthan 350° C.